Fin



FIG. 1 is a front isometric view of a fin showing our new design;

FIG. 2 is a rear isometric view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a rear view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof. 

The ornamental design for a fin, as shown and described. 